const path = require('path');
// path.jion方法用于智能拼接
console.log(path.join('a', 'b', 'c')); //a\b\c
console.log(path.join('a', 'b', 'index.html')); //a\b\index.html
console.log(path.join('a', 'b', '../c', 'index.html')); //a\c\index.html
// _dirname //得到任意文件的绝对路径
console.log(path.join(__dirname, '02-join.js', ));